Menu
Home
People
Places
Arts
History
Plants & Animals
Science
Life & Culture
Technology
Reference.org
Cytohet
open-in-new
<p>In <a href="/facts/Genetics/bu8wne0A">genetics</a>, a cytohet (or heteroplasmon) is a <a href="/facts/Eukaryotic/SkwyPLMA">eukaryotic</a> <a href="/facts/Cell_(biology)/bLM9UQvy">cell</a> whose <a href="/facts/Cell_nucleus/D7sFRa3c">non-nuclear</a> <a href="/facts/Genome/31Sm08JT">genome</a> is <a href="/facts/Heterozygous/XzEJ5gPp">heterozygous</a>. </p><p>The non-nucleic genome of eukaryotic cells exists in <a href="/facts/Cytoplasm/Wa0sE6xf">cytoplasmic</a> <a href="/facts/Organelle/vhDFnGbs">organelles</a>, namely the <a href="/facts/Chloroplast/fo8U3yTx">chloroplasts</a> (only in <a href="/facts/Plant_cell/T4RqyI2f">plant cells</a>) and the <a href="/facts/Mitochondria/ErHqrdJ1">mitochondria</a> (in all eukaryotic cells). </p><p>Most of the <a href="/facts/Gene/e1swwPY6">genes</a> in the mitochondria code for <a href="/facts/Cellular_respiration/kb6gpsvL">respiration</a>-related <a href="/facts/Protein/Jxmagu3E">proteins</a>, and most of the genes in the chloroplasts code for <a href="/facts/Photosynthesis/TMV7w693">photosynthesis</a>-related proteins. The cytoplasmic genome, in contrast with the nucleic genome, exists in many copies in each cell: each cell contains numerous mitochondria and/or chloroplasts, and each such organelle contains multiple copies of its <a href="/facts/Chromosome/FRGf11FC">chromosome</a>. </p><p><a href="/facts/Mutation/Ee4NnWbY">Mutations</a> in the cytoplasmic genome occur spontaneously and at a much higher rate than in the nucleus, since the mitochondria and chloroplasts are exposed to high <a href="/facts/Concentration/wqBmz5od">concentrations</a> of <a href="/facts/Reactive_oxygen_species/GpwSRugH">reactive oxygen species</a> (ROS, by-products of respiration and photosynthesis). Mitochondria and chloroplasts with mutant genes have the ability to cause <a href="/facts/Wildtype/Rr0vGvM0">wildtype</a> <a href="/facts/Allele/8FxCS9KA">alleles</a> in other mitochondria and chloroplasts to become mutant as well; the way in which this is done is still not clear. A certain cell in which a mutant gene exists only in some of the organelles, whereas the wildtype allele exists in the rest, is a cytohet (or heteroplasmon). </p>